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Subject: Re: Interesting search extension data

Author: Ren Wu

Date: 22:07:42 01/24/01

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Thanks Bob, for this is a interesting post.

On January 24, 2001 at 23:39:12, Robert Hyatt wrote:

>In the following test, I varied each of the 5 extensions in five steps,
>0.0, 0.25, 0.5, 0.75 and 1.0.  I treated each extension as an independent
>test, that is I did not run 5^5 test cases,
Actually 5^5 cases is even more intresting, can you, or will you do this in the
future?

>recapture is the most interesting case.  It actually appears that removing
>this _completely_ gave the best score, which is surprising since
>win at chess is a tactical suite.  Lowering this extension obviously
>speeds up the overall search.  I currently use .75 here as well.

>The most interesting thing is the recapture extension.  I have used it forever,
>and took the idea from Cray Blitz since I used it there as well.  I am not yet
>sure why it actually hurts since it seems (to me) to be a logical idea.  I am
>going to test this more, just for my own interest.

I never found recapture extension worthwhile in my program. However, i was more
depend on testsuite, not the games, so i am not sure if this can have any
benefit in real games.

Maybe you can try giving lost captures minus extension (prune) and see what
happens?

I used to think that fast computer will help more on extensions, but now i am
almost want to think in other ways around, that is, doing more prune likily
probably better than extends.

Ren.



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